Food insecurity, a household condition of limited food availability, affects 16 million US children today. Food- insecure children are at risk for adverse diet-related health conditions; however, the mechanisms underlying these associations have not been clearly identified. Chronic, psychological stress may represent an important pathway between food insecurity and childhood obesity. The effects of chronic stress on children's cognitive development and cardio-metabolic health have been well-documented. However, research of the psychological component of food insecurity is sparse. Understanding the psychosocial and cognitive mechanisms underlying children's experiences of food insecurity is important to inform the development of strategies to reduce children's food insecurity and its sequelae. I am pursuing a K99/R00 Pathway to Independence Award to fill critical training gaps in the areas of stress mechanisms and measurement, children's development of cognitive processes related to overeating, and causal mediation analysis. This award will build upon my advanced training as a nutrition epidemiologist and my prior research on the relations between participation in the federal food programs and diet-related chronic disease. The detailed training plan includes formal coursework at UCSF and UC Berkeley, meetings, seminars, readings, and research apprenticeships. The research component of my project will provide opportunities to integrate knowledge from these new areas. Through the proposed series of studies, I will test the hypothesis that household food insecurity increases children's psychological stress, which shapes their cognitive processes related to eating behaviors and food choice, and predicts subsequent weight gain. First, I will develop a measure to capture children's psychological stress of food insecurity, drawing from qualitative interviews with food-insecure children and existing measures of children's psychological stress. The measure's psychometric properties will be empirically tested in a separate sample of low-income children. Second, in a laboratory setting, I will determine the extent to which children's food insecurity-stress mediates the relationship between household food insecurity and children's cognitive processes related to overeating, using the newly developed measure. Finally, I will design and conduct a two- year longitudinal study to examine associations between household food insecurity and children's weight gain, and the extent to which this is mediated through the proposed pathway. This program of research will focus on children during the transition to adolescence (ages 8-12), a significant period for cognitive development and weight gain with lifelong implications. These findings will highlight a novel and important pathway to explain the adverse effects of food insecurity on children's developmental and diet-related outcomes. The proposed training plan and series of studies will provide me with a set of skills and expertise needed to successfully compete for funding as an independent investigator and to serve as a leader in developing interventions and policies to minimize food insecurity and promote health in low-income children.